The present invention relates to an IC card. More specifically, it relates to an IC card having a power supply.
Non-contact IC cards have been widely used in recent years, which have an integrated circuit (IC) capable of electronically storing information and a coiled antenna connected to the integrated circuit and capable of transmitting and receiving electromagnetic waves. In such a non-contact IC card, the antenna receives electromagnetic waves from a reader/writer, and the integrated circuit is driven using electric power generated through electromagnetic induction, thereby making communication with the reader/writer.
Incidentally, in recent years, there is a demand for such an IC card to allow the user to view and check the information stored in the IC card, such as the balance or points, anytime and anywhere he/she wants. In order to meet such a demand, JP-A-2007-280372 has proposed a technique in which a liquid-type secondary battery is mounted on an IC card, and the secondary battery drives a display device to display information. Further, JP-A-2003-273386 has proposed a technique in which a solar cell is mounted on an IC card so that the solar cell drives a display device.
However, according to the technique disclosed in JP-A-2007-280372, because a liquid-type electrolyte is used as the electrolyte of the secondary battery, the IC card has an increased thickness, impairing the advantages of the IC card being thin and flexible. In addition, there will be a liquid leakage incase of breakage, and this possibly short-circuits the electrical circuit or the battery. Mounting a liquid-type secondary battery on an IC card thus also has safety problems.
According to the technique disclosed in JP-A-2003-273386, it is difficult to display information, such as the balance, on the display device in an environment where sufficient light cannot be provided. Therefore, in order to improve the convenience of an IC card, it is desired to mount a secondary battery on the IC card.
Therefore, an object of the invention is to provide an IC card having a secondary battery, which causes no increase in thickness and also has excellent safety.